web/roll-carousel.html

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>jQuery carousel</title>
  <style>
  ul,
  li {
    margin: 0;
    padding: 0;

    list-style: none;
  }

  .carousel {
    position: relative;

    overflow: hidden;

    width: 1000px;
    height: 562.5px;
    margin: 40px auto;
  }

  .carousel .img-content {
    position: absolute;

    overflow: hidden;
  }

  .carousel .img-content>li {
    float: left;

    width: 1000px;
    height: 562.5px;
  }

  .carousel .img-content img {
    width: 100%;
  }

  .carousel .arrow {
    font-size: 2em;
    font-weight: 1000;
    line-height: 50px;

    position: absolute;
    z-index: 1;
    top: 50%;

    width: 50px;
    height: 50px;

    cursor: pointer;
    transform: translateY(-50%);
    text-align: center;
    text-decoration: none;

    color: white;
    border: 1px solid white;
    border-radius: 50%;
  }

  .carousel .pre {
    left: 30px;
  }

  .carousel .next {
    right: 30px;
  }

  .carousel .bullet {
    font-size: 0;

    position: absolute;
    bottom: 10px;
    left: 50%;

    transform: translateX(-50%);
    text-align: center;
  }


  .carousel .bullet>li {
    display: inline-block;

    width: 60px;
    height: 15px;
    margin: 0 5px;

    cursor: pointer;

    border: 1px solid white;
    border-radius: 4px;
  }

  .active {
    background: white;
  }
  </style>
</head>

<body>
  <div class="container">
    <div class="carousel">
      <ul class="img-content">
        <li><a href=""><img src="http://ov2hj85gi.bkt.clouddn.com/bing-daily-01.jpg" alt=""></a></li>
        <li><a href=""><img src="http://ov2hj85gi.bkt.clouddn.com/bing-daily-02.jpg" alt=""></a></li>
        <li><a href=""><img src="http://ov2hj85gi.bkt.clouddn.com/bing-daily-03.jpg" alt=""></a></li>
        <li><a href=""><img src="http://ov2hj85gi.bkt.clouddn.com/bing-daily-04.jpg" alt=""></a></li>
      </ul>
      <span href="" class="arrow pre">
        <</span>
      <span href="" class="arrow next">></span>
      <ul class="bullet">
        <li class="active"></li>
        <li></li>
        <li></li>
        <li></li>
      </ul>
    </div>
  </div>
  <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.js"></script>
  <script>
  var $nextBtn = $('.carousel .next');
  var $preBtn = $('.carousel .pre');
  var $imgContent = $('.carousel .img-content');
  var $img = $('.carousel .img-content li');
  var imgWidth = $img.width();
  var imgCount = $img.length;
  var $bullets = $('.bullet>li');

  var pageIndex = 0;

  var isAnimate = false;

  // 将第一张图片克隆到最后
  $imgContent.append($img.first().clone());
  // 将最后一张图片克隆到最前
  $imgContent.prepend($img.last().clone());

  // 动态设置img-content容器的宽度
  $imgContent.width((imgCount + 2) * imgWidth);

  // 将原始照片放置在正确位置
  $imgContent.css({ left: -imgWidth });

  $nextBtn.click(function() {
    playNext(1);
  });

  $preBtn.click(function() {
    playPre(1);
  });

  $bullets.click(function() {
    $this = $(this);
    var bulletIndex = $this.index();
    if (bulletIndex > pageIndex) {
      playNext(bulletIndex - pageIndex);
    } else if (bulletIndex < pageIndex) {
      playPre(pageIndex - bulletIndex);
    }
    clearInterval(auto);
  });

  function playNext(len) {
    if (isAnimate) return;
    isAnimate = true;
    $imgContent.animate({
      left: '-=' + len * imgWidth
    }, function() {
      pageIndex += len;
      if (pageIndex == imgCount) {
        pageIndex = 0;
        $imgContent.css({ left: -imgWidth }).fadeIn('slow');
      }
      setBullet();

      isAnimate = false;
    });
  }

  function playPre(len) {
    $imgContent.animate({
      left: '+=' + len * imgWidth
    }, function() {
      pageIndex -= len;
      if (pageIndex < 0) {
        pageIndex = imgCount - 1;
        $imgContent.css({ left: -imgWidth * imgCount });
      }
      setBullet();
    });
  }

  function setBullet() {
    $bullets.removeClass('active').eq(pageIndex).addClass('active');
  }

  // 设置自动轮播
    autoPlay =   setInterval(function() {
    playNext(1);
  }, 2000);
  </script>
</body>

</html>